This invention relates to printing presses, and more particularly to a new and improved cartridge assembly for providing a source of fabric net material to be used to cover the support surface of a transfer or delivery cylinder in a high speed, sheet fed off-set rotary printing press.
Disclosed in my U.S. Pat. No. 4,402,267 issued Sept. 6, 1983 and entitled "Method And Apparatus For Handling Printed Sheet Material", is a system for preventing the marking and marring of freshly printed sheets in a high speed, sheet fed off-set rotary printing press as the wet inked side of those sheets are supported by a transfer or delivery wheel or cylinder during transfer between processing stations within the press. That system, which has met with very substantial commercial success and worldwide acceptance in the printing industry, employs an ink repellent fabric material, referred to in the trade as a "net", loosely disposed over the support surface of the transfer or delivery cylinder, and which engages and clings to the wet ink side of the sheet as the sheet it being transferred over the cylinder.
As described in my aforementioned U.S Pat. No. 4,402,267, it is important that the net be properly tensioned over the cylinder so that the net remains relatively loose during operation. In my later U.S. Pat. No. 4,691,632 issued Sept. 8, 1987, there is disclosed a method and apparatus for attaching the anti-smear net to the cylinder so that the net may be readily and easily removed, installed and adjusted for proper tension. That later patent employs a pair of identical reel assemblies, one disposed adjacent the leading or gripper edge of the cylinder, and the other disposed adjacent the trailing or tail edge of the cylinder, and to which each end of the net is attached. By winding the net onto the reels, the proper tension of the net over the support surface of the cylinder can be maintained.
While the reel assemblies disclosed in my U.S. Pat. No. 4,691,632 have simplified the mounting of nets to the cylinder and the maintenance of proper net tension during the useful life of the net, the net must still periodically be replaced when it becomes soiled and/or worn out after prolonged use and begins to mark the sheets, or if the net is in some way damaged or torn during operation. It has been found that frequently the net will become soiled in only a small area, typically adjacent the leading or gripper edge, and that when this occurs, the entire net will have to be removed from the press and replaced with an entirely new net. This requires that the press be stopped and the old net removed from the cylinder. Thereafter, the entire new net must be reinstalled over the cylinder by attaching the ends to the gripper and tail edges of the cylinder, a process which can result in significant loss of press production time while the net is removed and a new net reinstalled.
Additionally, during operation of the press, the net material may be required to be adjusted to insure that the proper net tension over the cylinder is achieved for the particular printing job being run. This frequently requires that the press be stopped and the net tension adjusted by tightening the net slightly over the cylinder surface, since the net material may become stretched after prolonged use.
Thus, there exists a need for a new and improved method and apparatus for permitting only the soiled or damaged portion of the net to be quickly and easily replaced and/or the net tension adjusted with a minimum of lost press production time, yet which is simple, relatively inexpensive and highly reliable. As will become more apparent from the following detailed description, the present invention solves this need in a unique and unobvious way.